<template>
  <div id="app">
    <transition :name="transitionName">
      <router-view class="router-view" />
    </transition>
    <nav-bar v-if="isShowNav"></nav-bar>
  </div>
</template>

<script>
import navBar from '@/components/NavBar'
export default {
    data(){
      return{
        transitionName: 'slide-left',
        isShowNav: true,
        ShowMenuList: ['/','/home','/category','/cart','/user'],// 该变量为需要导航栏的数组
      }
    },
    components:{
      navBar
    },
    watch:{
      $route(to,from){
        // 通过 ES6 提供的 includes 属性判断 to.path 是否包含在数组内
        //console.log(to.path)
        if (this.ShowMenuList.includes(to.path)) {
          this.isShowNav = true
        } else {
          this.isShowNav = false
        }
         // 由主级到次级
        // to.meta 能取到 route 路由参数中的 meta 属性
        if (to.meta.index > from.meta.index) {
          // 通过改变变量名称控制左右滑动
          this.transitionName = 'slide-left' // 向左滑动
        } else if (to.meta.index < from.meta.index) {
          // 由次级到主级
          this.transitionName = 'slide-right'
        } else {
          this.transitionName = ''   //同级无过渡效果
        }
      }
    } 
}
</script>
<style lang="less" scoped>
#app {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color: #2c3e50;
}

#nav {
  position: absolute;
  top: 0;
  left: 50%;
  z-index: 1000;
}

.router-view{
    width: 100%;
    height: auto;
    position: absolute;
    top: 0;
    bottom: 0;
    margin: 0 auto;
    -webkit-overflow-scrolling: touch;
}

.slide-right-enter-active,
.slide-right-leave-active,
.slide-left-enter-active,
.slide-left-leave-active{
    height: 100%;
    will-change: transform;
    transition: all 500ms;
    position: absolute;
    backface-visibility: hidden;
}
.slide-right-enter{
    opacity: 0;
    transform: translate3d(-100%, 0, 0);
}
.slide-right-leave-active{
    opacity: 0;
    transform: translate3d(100%, 0, 0);
}
.slide-left-enter{
    opacity: 0;
    transform: translate3d(100%, 0, 0);
}
.slide-left-leave-active{
    opacity: 0;
    transform: translate3d(-100%, 0, 0);
}
</style>